The Goals of this core are: I. Maintain an active centralized core in order to provide: 1. Immunohistochemistry and histopathology. 2.High resolution electron microscopy and immuno-electron microscopy. 3. Confocal laser scanning microscopy. 4. Flow Cytometry. II. Ensure rigorous quality control and quality assurance on all samples evaluated by the core. This Core consists of four parts: the immunohisto-chemistry/histology laboratory, the electron microscopy laboratory, the flow cytometry laboratory and the confocal microscopy laboratory. The immunohistochemistry/histology lab provides a mechanism for accurate histopathologic characterization of the models in use. The lab also provides immunohistochemistry with excellent quality control leading to accurate and reproducible results allowing quantitative histochemistry and histopathology. The electron microscopy lab will provide not only routine EM but also in immuno-electron microscopy. The flow cytometry lab will be used to measure apoptosis using several different methods including TUNEL, Annexin V, and propidium iodide staining. Measurement of DNA levels for cell cycle analysis and ploidy determination will also be available. The confocal microscopy lab will provide 3-Demensional imaging and high resolution fluorescence quantitation. The core will be used by all 5 projects in this proposal. Performance sites: The immunohistochemistry/histology lab- Department of Pathology, UAMS, Little Rock, AR. The electron microscopy lab- CAVHS, Department of Pathology, Little Rock, AR. The flow cytometry lab- Department of Microbiology, UAMS, Little Rock, AR. The confocal microscopy lab- ACRC, Little Rock, AR.